EghtesadOnline: The head of the UN atomic watchdog is confident the US will not scupper Iran's nuclear deal, despite US President Donald Trump's criticism of the accord.

Yukiya Amano, director general of the International Atomic Energy Agency, told the Financial Times that the agreement, which Trump this month described as the "worst deal I've ever seen negotiated", was proving more durable than expected.

"As long as it is implemented, this agreement is more robust than many people think," Amano said, referring to the deal, which the IAEA monitors and verifies.

"Finding [an]other solution would be extremely difficult."

According to ILNA, he highlighted Iran's compliance with the agreement's provisions and said that Republicans in the US Congress were growing more aware of the benefits provided by the deal.

"I don't claim the verification system is perfect, but it is the best we can expect under the circumstances," Amano said, while making clear it was not up to Washington alone to decide whether to keep or ditch the deal.

"This is not bilateral; this is not an agreement among several [parties], but the whole international community."

But the IAEA chief conceded that tensions caused by issues not included in the accord—such as Iran's missile program—could undermine confidence.

***Decisive Elections

Amano also acknowledged that the fate of Hassan Rouhani, Iran's centrist president who faces reelection in May, was another cause of uncertainty.

"Anything can influence the situation; this is the difficulty," Amano said, when asked about Iran's missile tests. "A small technical thing related to implementation can become a big political issue … Confidence is very limited."

He added that while Rouhani was "very committed" to the deal, "if he loses [the election] it is a different thing."

Tehran struck the agreement with six world powers in 2015 after years of diplomatic effort. The accord was one of the big accomplishments of the Barack Obama administration.

Its provisions allow IAEA inspectors much greater access to Iran's nuclear facilities, while also reining in the country's atomic activities, which Tehran says are only meant for peaceful purposes.

Under the deal, Tehran agreed to ship out part of its stockpile of enriched uranium. In return, western nations lifted nuclear-related sanctions on the Islamic Republic.

But Trump argues that the US has "nothing to show" for the deal and has declined to confirm or deny whether he intends to follow through on his campaign promises to unravel the agreement.

Rex Tillerson, Trump's secretary of state, has called for a full review of the deal.

US tensions with Iran have risen on other fronts, too, with the White House saying it was putting Iran "on notice" after Tehran test-fired a ballistic missile in late January.

The Trump administration imposed further sanctions on a number of individuals and entities allegedly linked to Iran's missile program after the launch.

The IAEA chief said that while Republicans in Congress were "very much opposed" to the deal, "the gain from the verification point of view is better understood now".

Amano added that Tehran insists it would not violate the deal.

"They keep on saying that Iran will not be the first to break the agreement and so far they are doing it."